Control and Coordination Class 10 Notes Science

 

Control and Coordination 

1. What is Control and Coordination?

• Control and coordination are the processes that help living organisms control their body activities and respond to changes around them. These processes are crucial for survival, growth, and maintaining balance in their internal environment. 

• The two major systems responsible for control and coordination in humans are:

  1. Nervous system — works mainly through electrical impulses.

  2. Endocrine system — works through chemical messengers called hormones.

• Plants do not have a nervous system or muscles, but they coordinate their responses through chemical signals (hormones ) and growth-related movements.

2. Why do organisms need control and coordination?

• To detect changes in the environment.

• To respond appropriately to different stimuli.

• To protect themselves from danger.

• To coordinate the activities of different organs.

• To maintain proper growth and functioning.

3. Stimuli

• The changes in the environment to which the organisms respond is called stimuli such as light, heat, cold, sound, smell, touch etc.
• Plants and animals both respond to stimuli but in different manner.

4.  Control and Coordination in Animals

4.1 Receptors

Receptors are specialised nerve cells which initiate waves of impulses towards the central nervous system on receiving a stimulus.

These are classified as follows :

• Phono-receptors: These are present in inner ear.
  Functions: The main functions are hearing and balance of the body.
• Photo-receptors: These are present in the eye.
  Function: These are responsible for visual stimulus.
• Thermo-receptors: These are present in skin.
  Functions: These receptors are responsible for pain, touch and heat stimuli.
  These receptors are also known as thermoreceptors.
• Olfactory-receptors: These are present in nose.
  Functions: These receptors receive smell.
• Gustatory-receptors: These are present in the tongue.
  Functions: These helps in taste detection.

Example: When we smell an incense stick, olfactory receptors in the nose detect the smell and send signals through sensory nerves towards the brain.

4.2 Nervous System

Basic unit: Neuron

Neuron: A neuron is the structural and functional unit of the nervous system. 

A neuron is a specialised nerve cell that receives and transmits information through electrical impulses.

Its main parts are:

• Dendrites: These are branched structures that receive nerve impulses from receptors or other neurons and carry them towards the cell body.

• Cyton or cell body: The cell body or cyton is somewhat star-shaped, with many hair like structures protruding out of the margin.It contains the nucleus and cytoplasm. It controls the activities of the neuron and maintains the cell.

• Axon: This is the tail of the neuron.It is a long, fibre-like structure that carries nerve impulses away from the cell body to another neuron, muscle or gland.

• Nerve endings: These are the branched ends of the axon that transmit the nerve impulse to another neuron, muscle or gland through a synapse.

Transmission of a nerve impulse

The sequence is:

1. A stimulus is detected by a receptor.

2. A chemical reaction generates an electrical impulse at the receiving end of the neuron.

3. The impulse travels from the dendrite towards the cell body and along the axon.

4. At the axon ending, chemicals are released.

5. These chemicals cross the synapse and initiate an impulse in the next neuron, or communicate with an effector cell.

Types of neuron

Neurons are classified into three types on the basis of their functions:

1. Sensory Neurons: These neurons carry nerve impulses from receptors or sense organs to the central nervous system (brain and spinal cord).

2. Motor Neurons: These neurons carry nerve impulses from the central nervous system to effectors, such as muscles or glands, to produce a response.

3. Association Neurons (Relay Neurons): These neurons are present in the central nervous system and transmit nerve impulses between sensory neurons and motor neurons.

Remember:

• Sensory neuron — carries impulses towards the CNS.

• Motor neuron — carries impulses away from the CNS.

• Relay neuron — connects neurons within the CNS.

Structure of the Human Nervous System

The human nervous system controls and coordinates the activities of the body by receiving information, processing it and transmitting instructions to different body parts.

It consists of the following parts:

1. Central Nervous System (CNS): It consists of the brain and spinal cord. It receives and processes information and coordinates the responses of the body.

2. Peripheral Nervous System (PNS): It consists of nerves that connect the central nervous system to different parts of the body. It carries messages to and from the CNS.

3. Autonomic Nervous System (ANS): It regulates involuntary activities of the body, such as heartbeat, digestion and glandular secretion.

Human Brain

The human brain is the main coordinating centre of the nervous system. It receives information from different parts of the body, processes it and sends instructions to bring about appropriate responses.

Main Parts of the Human Brain

The human brain is divided into three main regions:

1. Forebrain

The forebrain is the main thinking part of the brain. It performs the following functions:

• Cerebrum: The cerebrum is the largest part in the human brains. It is divided into two hemispheres called cerebral hemispheres.

• Function : It controls thinking, memory, intelligence, learning and voluntary actions. Its sensory areas receive and interpret information from sense organs.

• Hypothalamus: The hypothalamus lies at the base of the cerebrum.

• Regulates hunger, thirst, body temperature and certain emotional responses.It controls sleep and wake cycle  of the body.

2. Midbrain

• The midbrain sits in the middle of our head, connecting the top and bottom parts of the brain.

• Controls certain reflex movements in response to visual and auditory stimuli.

• Helps coordinate responses to sensory information.

3. Hindbrain

The hindbrain consists of the cerebellum, pons and medulla.

• Cerebellum: It is located below the cerebrum, at the back of the brain.It has numerous folds and furrows.

• Maintains posture and balance and coordinates muscular movements to ensure precision.

• Medulla: It is a part of the hindbrain, located at the base of the brain and continuous with the spinal cord.

• Controls involuntary activities such as heartbeat, breathing, blood pressure and vomiting.

• Pons: The pons is a rounded bulge on the brainstem, located above the medulla and below the midbrain. 

• Helps regulate breathing and connects different parts of the brain.

Spinal Cord

The spinal cord is a long, cylindrical bundle of nervous tissue that extends from the medulla oblongata of the brain. It is protected by the vertebral column (backbone).

Functions of the Spinal Cord:

1. It conducts nerve impulses between the brain and different parts of the body.

2. It acts as the reflex centre and controls reflex actions, enabling quick responses to stimuli without waiting for instructions from the brain.

Example: When we touch a hot object, the spinal cord coordinates a quick response that causes us to withdraw our hand.

Protection of the brain and spinal cord

• Brain: Protected by the skull, or cranium. It is also surrounded by protective membranes and cerebrospinal fluid, which helps absorb shocks.

• Spinal cord: Protected by the vertebral column, or backbone.

4.3  Synapse

A synapse is the tiny gap between the nerve ending of one neuron and the dendrite or cell body of another neuron. It helps in the transmission of nerve impulses from one neuron to another through chemical messengers called neurotransmitters.

Neuromuscular Junction (NMJ)

A neuromuscular junction is the junction between the nerve ending of a motor neuron and a muscle fibre. When a nerve impulse reaches this junction, chemical messengers are released that stimulate the muscle fibre to contract.

Transmission of Nerve Impulses

Nerve impulses travel through a neuron in the following sequence:

Dendrites → Cell body → Axon → Nerve endings → Synapse → Next neuron

5. Reflex Action and Reflex Arc

5.1 Reflex Action

A reflex action is a quick, automatic and involuntary response to a stimulus that occurs without conscious thinking. It helps protect the body from injury.

Examples:

• Pulling the hand away from a hot object.

• Blinking when an object suddenly approaches the eye.

• Withdrawing the foot after stepping on a sharp object.

5.2 Reflex Arc

A reflex arc is the pathway followed by nerve impulses during a reflex action.

The pathway of a reflex arc is:

Stimulus → Receptor → Sensory neuron → Spinal cord (relay neuron) → Motor neuron → Effector → Response

Example: When we touch a hot pan, receptors in the skin detect the heat and generate nerve impulses. The sensory neuron carries the impulses to the spinal cord, where a relay neuron passes them to a motor neuron. The motor neuron carries the impulses to the arm muscles, causing the hand to withdraw quickly.

5.3 Why is the Spinal Cord Involved in Reflex Actions?

The spinal cord acts as the reflex centre and coordinates many reflex actions without waiting for conscious processing by the brain. This allows the body to respond quickly and reduces the risk of injury.

5.4Voluntary and involuntary actions

Voluntary actions are actions performed under conscious control.

Examples: writing, speaking and deliberately moving a chair.

Involuntary actions are actions that occur without conscious control.

Examples: heartbeat, digestion and regulation of blood pressure.

The medulla in the hindbrain controls several involuntary activities.

5.5  Difference between reflex action and voluntary action

Reflex action	Voluntary action
Rapid and automatic.	Performed by conscious decision.
Does not require deliberate thinking before the response.	Involves decision-making by the brain.
Often coordinated through the spinal cord.	Generally planned and controlled by the brain.
Example: withdrawing a hand from a flame. 6. Endocrine System and Hormones 1. Endocrine System The endocrine system consists of a group of ductless glands that secrete chemical substances called hormones directly into the bloodstream.  These hormones regulate various activities of the body and work along with the nervous system to bring about control and coordination. Hormones Hormones are chemical messengers secreted in small amounts by endocrine glands that regulate and coordinate various activities of the body. Hormones are released into the blood and carried to their target organs or tissues. Functions of Hormones They regulate growth and development. They control metabolism and blood sugar levels. They regulate changes during puberty and reproduction. They help the body respond to stressful situations. They coordinate activities that require slower and longer-lasting responses than many nervous responses. Difference between nervous and hormonal control Nervous control Hormonal control Uses electrical impulses along neurons and chemical transmission at synapses. Uses chemical messengers called hormones. Generally produces rapid responses. Generally produces slower responses. Effects are often short-lived and localised. Effects may last longer and act on distant target organs. 2. Important Endocrine Glands and Their Functions 1. Pituitary Gland It is located at the base of the brain. It secretes growth hormone, which regulates body growth. Deficiency of growth hormone during childhood may cause dwarfism, while excessive secretion may cause gigantism. It also secretes hormones that regulate the activities of other endocrine glands. The pituitary is often called the master gland because it controls several other endocrine glands. 2. Thyroid Gland It is located in the neck, in front of the windpipe. It secretes thyroxine, which regulates metabolism, including the metabolism of carbohydrates, proteins and fats. Iodine is essential for the production of thyroxine. A deficiency of iodine in the diet may cause goitre, characterised by enlargement of the thyroid gland. 3. Adrenal Glands A pair of adrenal glands is located above the kidneys. They secrete adrenaline, which prepares the body to deal with emergency situations. Adrenaline increases the heartbeat, breathing rate and blood supply to skeletal muscles, helping the body respond to danger. This is known as the fight-or-flight response. 4. Pancreas The pancreas is located in the abdomen, near the stomach. It acts as both an endocrine and an exocrine gland. It secretes insulin, which helps regulate blood glucose levels. Insufficient insulin production or ineffective insulin action can lead to diabetes mellitus. 5. Testes (Male Gonads) The testes are a pair of male reproductive organs located in the scrotum. They secrete testosterone. Testosterone brings about changes in boys during puberty, such as facial hair growth, deepening of the voice and development of reproductive organs. 6. Ovaries (Female Gonads) The ovaries are a pair of female reproductive organs located in the pelvic cavity. They secrete oestrogen and progesterone. Oestrogen helps bring about female secondary sexual characteristics during puberty. Progesterone helps regulate the menstrual cycle and supports pregnancy. 3. Summary Table: Endocrine Glands, Hormones and Functions Endocrine gland Hormone Main function Pituitary Growth hormone Regulates body growth Thyroid Thyroxine Regulates metabolism Adrenal Adrenaline Prepares the body for emergencies Pancreas Insulin Regulates blood glucose Testes Testosterone Develops male secondary sexual characteristics Ovaries Oestrogen Develops female secondary sexual characteristics Ovaries Progesterone Supports the menstrual cycle and pregnancy	Example: writing an answer or picking up a book.

class 11 Geography Chapter 1 Geography as a Discipline

 

Chapter 1 Geography as a Discipline

Q1. What is Geography?

Answer: Geography is the study of the Earth’s surface, physical features, human activities and the relationship between humans and their environment. It studies both natural and human phenomena and their spatial distribution.

Q2. Why is Geography called an integrating discipline?

Answer: Geography is called an integrating discipline because it studies the interrelationship between physical and human phenomena.

It integrates:

• Physical geography – landforms, climate, oceans, soils, vegetation etc.
• Human geography – population, settlements, agriculture, industries etc.
• Regional geography – study of a particular region as a whole.

Thus, geography provides a holistic view of the Earth and human life.

Q3. What are the two major branches of Geography?

Answer: The two major branches are:

1. Physical Geography – deals with natural features and processes of the Earth.
2. Human Geography – deals with human activities and their relationship with the environment.

Q4. What is Physical Geography?

Answer: Physical Geography studies the physical environment of the Earth and the processes responsible for its formation and changes.

Its major branches include:

• Geomorphology – study of landforms
• Climatology – study of climate
• Oceanography – study of oceans
• Biogeography – study of living organisms and their geographical distribution

Q5. What important cultural features do you observe while going to school? Are they similar or dissimilar? Should they be included in the study of geography or not? If yes, why?

Answer : When we go to school we see shops, theatres, roads, temple, mosque, church, gurudwara, houses,hospitals, government offices, etc on the way. These represent cultural features.

All the cultural features are dissimilar due to the technology used in making them.

Yes, they must be included because they represent human footprints on physical space, forming the foundation of Human Geography.

Q6. Do you celebrate Van Mahotsava in your school? Why do we plant so many trees? How do the trees maintain ecological balance?

Answer : Yes, we celebrate Van Mahotsava in our school. We plant so many trees as these increase the forest area of our country. These are necessary to maintain the ecological balance and for the conservation of the environment.

Q7. Mention the three sets of questions that analytical geography seeks to answer.

Answer: 

• What: Identifies the natural and cultural features found on the Earth's crust.
• Where: Pinpoints the precise locations and distribution patterns of these features.
• Why: Investigates the causal relationships and factors that explain why features occur where they do.

Class 12 History Chapter 4: Thinkers, beliefs and buildings

 Chapter 4: Thinkers, beliefs and buildings

Q1. Name two sects of Buddhism.

Ans. The two sects of Buddhism are Hinayana and Mahayana.

Q2. What is the most important idea in Jainism?

Ans. The most important idea in Jainism is that the entire world is animated.

Q3. Define 'Tirthankara'.

Ans. In Jainism, a Tirthankara is a saviour and spiritual teacher of the dharma (righteous path).

Q4. Define the concept of Bodhisatta. 

Ans. Bodhisatta were perceived as deeply compassionate beings who accumulated merit through their efforts, but used this not to attain nibbana and there-by abandon the world, but to help others.

Q5. Who started Jainism?

Ans. Rishabdev was the first Tirthankara and Mahavira was the 24th Tirthankara of Jainism.

Q6. What did Queen Kamalavati ask the king to renounce?
Ans. Queen Kamalavati ask the king to renounce the world, the kingdom, abandon what pleases the senses, be without attachment and renounced the pleasures.

Q7. What did Buddha's stupas represented?
Ans. The Buddha's stupas represented Mahaparinibbona.

Q8. Differentiate between Vaishnavism and Shaivism. 

Ans. The worship of Lord Shiva is known as Shaivism and the worship of Lord Vishnu is known as Vaishnavism.

Q9. Why were the stupas venerated? 

Ans. The stupas were venerated as relics of the Buddha such as his bodily remains or objects used by him were buried there.

Q10. What did the early Buddhist teachings give importance to?

Ans. Early Buddhist teachings gave importance to self-efforts in achieving Nibbana. 

Q11. During the nineteenth century, why the Europeans were interested in the stupa? Give two reasons. 

Ans. Europeans were interested in stupa because:
(i) British official named Colin Mackenzie found several pillars of sculpture and made detailed drawings of them. These reports were never published in order to protect the stupa.
(ii) 19th century Europeans, like the French and English sought Shahjehan Begum's permission to take away the Eastern gateway which was best preserved to be displayed in museums in France and England.
(iii) Cunningham took drawing of the place, deciphered the inscriptions and bored shafts down these domes. This happened partly because those who considered them to be beautiful and valuable wanted to keep it for themselves.

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Class 12 History : 3 Kinship, Caste and Class

 Kinship, Caste and Class

Q1. Explain how you will prove that the text of Mahabharata was a dynamic one.

Answer : The following points prove that the text of Mahabharata was a dynamic one: 

(i) Written in Many Languages: The growth of the Mahabharata did not stop with the composition of the Sanskrit version. Over the centuries, it has been written in many languages through an ongoing process of dialogues between people, communities and those who wrote the texts. 

(ii) Several Stories: As it incorporated several stories that originated in different regions, the Mahabharata became an epic text. 

(iii) Wide Range of Themes: They also provide a wide range of themes and performing arts like plays, dance and narratives.

Q2. Explain why patriliny may have been particularly important among elite families.

Answer : Patriliny was particularly important among elite families because:

1. Inheritance of property: Under patriliny, property and wealth were generally passed from the father to his sons.
2. Continuation of family lineage: It ensured that the family name, status and lineage continued through the male descendants.
3. Political power: In ruling families, the throne and political authority were usually inherited by sons. This helped maintain control over kingdoms and territories within the same family.
4. Preservation of wealth and status: Elite families owned large amounts of land, wealth and other resources. Patrilineal inheritance helped keep these within the family.

Thus, patriliny helped elite families preserve their property, political power, social status and family lineage across generations.

Q3. In what ways was the Buddhist theory of a social contract different from the Brahmanical view of society derived from the Purusha Sukta?

Answer : The Buddhist theory of social contract differed from the Brahmanical view derived from the Purusha Sukta in the following ways:

1. Origin of society:
   According to the Buddhist tradition, society developed through a mutual agreement among human beings. People chose a ruler to maintain order and punish wrongdoers. Thus, social organisation was considered a result of human choice and agreement.
2. Brahmanical explanation:
   The Purusha Sukta explained the origin of the four varnas as divine. Brahmanas emerged from the mouth, Kshatriyas from the arms, Vaishyas from the thighs, and Shudras from the feet of Purusha.
3. Basis of social position:
   The Brahmanical system associated social position with birth and prescribed duties, whereas the Buddhist tradition placed greater emphasis on individual conduct and actions rather than birth.
4. Role of the king:
   In the Buddhist theory, people selected a ruler and agreed to give him a share of their produce in return for protection and maintenance of order. This made kingship a result of a social agreement.

Conclusion:
Thus, the Brahmanical view presented social divisions as divinely ordained, while the Buddhist theory explained social order as a human creation based on agreement, needs and actions.

Q4. Explain the duties of the Chandalas as strictly laid down in the Manusmriti.

Answer: According to the Manusmriti, the Chandalas were considered untouchables and were placed outside the social order. Their duties and living conditions were strictly regulated:

1. Living outside the village: They were required to live outside the village boundaries and were allowed to use only discarded utensils.
2. Clothing and ornaments: They had to wear clothes taken from the dead and could wear only iron ornaments.
3. Restricted movement and duties: They were not allowed to enter villages at night. They were assigned tasks such as working as executioners and disposing of the bodies of people who had no relatives.

Q5. Describe the fundamental rules of marriage as prescribed by the Brahmanical texts. 

Answer: Brahmanical Rules Regarding Marriage

1. Exogamy: Brahmanical texts encouraged exogamy, which means that a person should marry outside their own gotra or kin group. Marriage within the same gotra was generally prohibited.
2. Eight Forms of Marriage: Brahmanical texts mentioned eight different forms of marriage. The first four were considered acceptable and respectable, while the other four were condemned or disapproved of.
3. Kanyadana: Kanyadana literally means the gift of a daughter. According to Brahmanical traditions, it was considered the religious duty of the father to give his daughter in marriage to a suitable man, thereby maintaining the family lineage and social order.

Q6. Explain the concept of ‘Gotra’ and state its two main rules regarding women.

Answer:

1. Meaning of Gotra: In Brahmanical practice, people were classified into gotras, which were named after Vedic seers (rishis). Members of a gotra were considered to have descended from a common ancestor.

    2.Rule for women after marriage: i.Women were expected to give up their father’s                gotra  after marriage and adopt the gotra of their husband.

        ii. Members of the same gotra were not allowed to marry each other. Marriage was             expected to take place outside one’s own gotra. This practice is called exogamy.

Q7. Discuss whether gender differences were important in early societies regarding access to property.

 Answer:

1. Paternal Estate and Sons' Rights:

• Gender differences were crucial, as the Manusmriti explicitly stated that the paternal estate was strictly divided equally among sons, while women had no claim.

2. Women and Stridhana:

• Women were legally permitted to retain gifts received during marriage (stridhana), which could be inherited by their children without the husband having any legal claim.

3. Restrictions on Women's Wealth:

• However, women were generally forbidden from hoarding family property or personal wealth without their husband’s permission, highlighting severe economic subordination and limited independence.

Q8. Explain the complexities involved in compiling the critical edition of the Mahabharata. What did it reveal?

Answer:

1. Beginning of the Project:

• The monumental project of compiling the critical edition began in 1919 under the dedicated leadership of the eminent Sanskrit scholar V.S. Sukthankar.

2. Collection of Manuscripts:

• A massive team of scholars collaborated to painstakingly collect ancient Sanskrit manuscripts of the text from various regions across the entire Indian subcontinent.

3. Different Regional Scripts:

• These historical manuscripts were written in a wide variety of regional scripts, demanding extensive linguistic expertise to translate, decipher, and accurately compare them.

4. Comparison of Verses:

• The scholars established a meticulous method of comparing verses, ultimately selecting only those verses that appeared commonly across virtually all the manuscript versions.

5. Massive Critical Edition:

• The resulting critical edition was massive, eventually published in multiple volumes running into over 13,000 pages after nearly 47 years of scholarly work.

6. Commonality Across India:

• This exhaustive process highlighted a remarkable underlying commonality in the Sanskrit text across the vast country, from Kashmir down to Kerala.

7. Regional Variations:

• However, the project also uncovered numerous regional variations and local interpolations that had subtly seeped into the epic over many centuries of transmission.

8. Documentation of Variations:

• These complex variations were carefully documented as vital footnotes and appendices, reflecting the dynamic, evolving nature of ancient India’s rich social history.

Class 12 History Chapter 1 Bricks, Beads and Bones The Harappan Civilisation

Bricks, Beads and Bones The Harappan Civilisation

Class 9 Science Chapter 1 Matter in Our Surroundings NCERT Solutions

 Chapter 1 

Matter in Our Surroundings

Q1. Which of the following are matter?
Chair, air, love, smell, hate, almonds, thought, cold, cold-drink, smell of perfume.
Answer: Chair, air, almonds, cold drink and smell of perfume.

Q2. Give reasons for the following observation:
The smell of hot sizzling food reaches you several meters away, but to get the smell from cold food you have to go close.
Answer: We know that, with an increase in temperature of a substance the kinetic energy of a substance increases, and hence  rate of diffusion of gas increases . 

Thus, the smell of hot sizzling food reaches you several meters away, but to get the smell from cold food you have to go close.

Q 3. A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Answer: This shows that the particles of water have intermolecular space between them .

Q 4. What are the characteristics of the particles of matter?
Answer. The characteristics of the particles of matter are:
(1) Particles have inter-molecular space.
(2) Particles have inter-molecular force.
(3) Particles of matter are moving continuously.

Q 5. The mass per unit volume of a substance is called density.
(density = mass/volume).
Arrange the following in order of increasing density: air, exhaust from chimneys, honey, water, chalk, cotton and iron.
Answer: Increasing density:
air < exhaust from chimneys < cotton < water < honey < chalk < iron.

Question 2. (a) Tabulate the differences in the characteristics of states of matter.
(b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.
Answer: (a) Difference in the characteristics of 3 states of matter.